I'm so sorry, but I need to reschedule our appointment on (date) at (time). When I set the meeting up with your assistant, I forgot that I had already committed to another meeting. I realize changing the appointment may be an inconvenience to you and I apologize. If... Dear (recipient's name),
I'm so sorry, but I need to reschedule our appointment on (date) at (time). When I set the meeting up with your assistant, I forgot that I had already committed to another meeting. I realize changing the appointment may be an inconvenience to you and I apologize. If possible, I would like to reschedule for (date) at (time). I have double checked my calendar and I am available this day. If this works for your schedule, please give me a call at (phone number).
Sincerely,
(your name)